• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

12v 3a or gate - 6 isolated inputs, 1 common output

Status
Not open for further replies.

Dan Gengler

New Member
I am looking for the most efficient design for controlling one output with any one of six inputs. This is to run a 12 v solenoid, 12v in, 12v out. 3 amp would be plenty but prefer to overbuild. Six 1N5400s??
 
Last edited:

spec

Well-Known Member
Most Helpful Member
Hi DG,

Six 1n4148 small- signal diodes, two resistors, and one MOSFET will do the job nicely.

spec
 

Dan Gengler

New Member
Appreciate that spec, are you thinking the six diodes tied to source of a IRFZ44N FET with a resister pull to ground, gate to ground and drain to solenoid with another resister to ground? What size resistors are you thinking? I got my associates in 1989 and did not stay in the field so pretty rusty.. But I do remember "Bad Beer Rots Our Young Guts But Vodka Goes Willingly " :)
 

AnalogKid

Well-Known Member
Most Helpful Member
A decent question, a decent answer, no arduinos and no 555s - this place is falling apart.

ak
 

Dan Gengler

New Member
Again, I really appreciate that spec. Neat and clean with all of the safeties, Going to go ahead build one and play with it.

Now, I'm going ask... Is there a simpler, "less clean" way to do this? My 12v source is a car battery/alternator, my load is a continuous duty starter solenoid running a motor/hydraulic pump. As you might assume, I will have six individual functions that will require the hydraulic pump to run. These functions will be run by toggle switches switching the +12v...the solenoid along with everything else will be chassis grounded. Noise will probably not be an issue.. Nor will a little voltage drop. Now you're probably going to say, wow this guy wasn't worth my time and I apologize for that but when I said six 1N5400 in my first post, I was somewhat serious. Can I tie the six Cathode ends of the 1N5400 diodes together with the load and use the six Anode ends as my inputs? Some diodes, heat shrink and terminal connectors in my wiring harness and done... I should add that the run time of each function will be less than 5 min, probably more like 1 to 2 minutes. Also it is probable that more than one input could be used at any one given time.
 
Last edited:

JimB

Super Moderator
Most Helpful Member
Now, I'm going ask... Is there a simpler, "less clean" way to do this?
Yes.

You could do this...
Simplified Solenoid Driver.png

...which is simpler.
The 12v supply from the individual switches comes in on each of the inputs.
The diodes would have to be rated for the solenoid current, (maybe use 1N5400), the 1N4148 would be instantly transported to "Silicon Heaven" if used in this circuit.

With this circuit the switches would also have to be rated for the solenoid current, whereas with specs circuit you could use smaller, lower current, (cheaper ?) switches.

So many ways to skin the proverbial moggy!

JimB
 

spec

Well-Known Member
Most Helpful Member
Again, I really appreciate that spec. Neat and clean with all of the safeties, Going to go ahead build one and play with it.

Now, I'm going ask... Is there a simpler, "less clean" way to do this? My 12v source is a car battery/alternator, my load is a continuous duty starter solenoid running a motor/hydraulic pump. As you might assume, I will have six individual functions that will require the hydraulic pump to run. These functions will be run by toggle switches switching the +12v...the solenoid along with everything else will be chassis grounded. Noise will probably not be an issue.. Now you're probably going to say, wow this guy wasn't worth my time and I apologize for that but when I said six 1N5400 in my first post, I was somewhat serious. Can I tie the six Cathode ends of the 1N5400 diodes together with the load and use the six Anode ends as my inputs? Some diodes, heat shrink and terminal connectors in my wiring harness and done... I should add that the run time of each function will be less than 5 min, probably more like 1 to 2 minutes. Also it is probable that more than one input could be used at any one given time.
Hello DG,

For from saying that your thread is time wasted, I now understand what you were saying in your original post.

I did not realise that the input signal was capable of supplying the 3A to drive your solenoid.

Yes, you can connect the cathodes of as many diodes as you like to the solenoid.

The circuit will then work like this, which in logic is called an 'OR' function (gate):

(1) No inputs switched to 12V: solenoid not energized
(2) Any combination of of inputs switched to 12V from one switch to all six switches: solenoid energized.

There will be in no interaction between the inputs, that is the nature of a logic gate.

There is just a practical issue though: an 1N5400 diode will not be suitable for the job. I will advise further- wife wants me to eat lunch.:)

spec
(posts crossed Jim)
 
Last edited:

Dan Gengler

New Member
Again, I appreciate everyone's input and apologize, should have been more descriptive to begin with..and the word "efficient"wasn't the best choice of words. For some reason I can't quickly find the current draw for the coil on the solenoid but my guess is around that 1 amp area. As mentioned I want to overbuild.. I guess a Bosch type relay with a separate source could be added if necessary.
 
Last edited:

spec

Well-Known Member
Most Helpful Member
Hi DG,

Jim has the circuit in post #7.

About the diodes specification that I mentioned in post #8.

You may say, I have a 3A solenoid and the 1N5400 diodes are rated at 3A, so what is the problem. But, I am afraid it is more complicated than that, and there are many factors that affect the diode selection. I wont bore you with all the details except to say that an industrial/automobile environment is particularly hazardous. There is a special grade of components that should be used in demanding environments, but for this application standard grade components will be OK (but definitely not if any safety critical aspects are involved).

For your application I would recommend using Schottky diodes, of at least 6A rating.

Also, the diodes should be in free air and not covered in any thermal insulating material, like heat shrink sleeve.

There are some diodes that are very popular, and hence low cost, and for your application I would recommend the MBR10100.

You may as well use the MBR100 for the catching diode (to protect the input switches) across the coil as shown in the schematic of post #8

You will need to mount the diodes on a heatsink (metal plate or chassis will do) with a mounting kit (insulating washer, insulating bushes and nut and bolts). If you at not familiar with this mounting method just ask and we will explain.

spec

DATASHEET

(1) http://www.onsemi.com/pub_link/Collateral/MBR1080-D.PDF
 
Last edited:

Dan Gengler

New Member
Again, thanks I say! Your ??? Link isn't working. Also I was in the process of adding to previous post #9, not sure if you caught that.
 

spec

Well-Known Member
Most Helpful Member
Again, I appreciate everyone's input and apologize, should have been more descriptive to begin with..and the word "efficient"wasn't the best choice of words. For some reason I can't quickly find the current draw for the coil on the solenoid but my guess is around that 1 amp area. As mentioned I want to overbuild.. I guess a Bosch type relay with a separate source could be added if necessary.
OK- got the fact that you think that the coil is 1A and not 3A, so the 1N5400 diodes will be adequate (by the way the 1N5400 is obsolete). But the diodes must be in free cool air and not covered in insulating material.

If you haven't got the diodes already go for a 3A or higher schottky diode like the SB5100 for example

The '???' was not a link- just a place holder while I got the information.

spec

UPLOADS
 

Attachments

Last edited:

Dan Gengler

New Member
Got it, thanks spec (and Jim). I will confirm the coil draw and build accordingly keeping the diodes uncovered for heat dissipation. I really appreciate everyone's assistance on this! Have a great day!
 

spec

Well-Known Member
Most Helpful Member
No probs from me DG.

Hope it all turns out OK.:)

spec
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top